Self-purging disk system

ABSTRACT

A closed system designed to have a minimum, and preferably no foreign particles in its interior, includes an enclosure housing a rotating mass which develops pressure differentials in the fluid enclosed in the housing. A conduit having a filter therein for collecting particles over a selected size connects an outlet port with an inlet port which are located adjacent areas of high pressure and low pressure, respectively, with the difference in pressure being sufficient to carry the particles through the conduit with the fluid movement therethrough.

United States Patent [72] Inventor RobertGeorgeGroom 3,110,889 11/1963 Morley et a1 340/1741 Thousand Oaks, Calif. 3,179,945 4/1965 Shapiro 340/1741 [21] AppLNo. 832,930 3,319,236 5/1967 l-lajen 340/1741 [22] Filed June 13, 1969 3,381,285 4/1968 Wallen 340/1741 [45] Patented Dec- 28, 1971 3,303,485 2/1967 Lee 340/1741 [73] Asslgnee gzy x g Primary Examiner-Bernard Konick Assistant Examiner-Vincent P. Canney Attorney-Christie, Parker & Hale [54] SELF-PURGING DISK SYSTEM 5 Claims 5 Drawmg Figs ABSTRACT: A closed system designed to have a minimum, [52] US. Cl ..340/174.1 E, and preferably no foreign particles in its interior, includes an 55/17, 55/467, 179/1002? enclosure housing a rotating mass which develops pressure [51] lnt.Cl Gl1b5/40, differentials in the fluid enclosed in the housing. A conduit BOld 45/18 having a filter therein for collecting particles over a selected [50] Field of Search 179/1002 size connects an outlet port with an inlet port which are P, 100.2 C; 340/174.l F, 174.1 E; 55/467, 17 located adjacent areas of high pressure and low pressure, respectively, with the difference in pressure being sufficient to [56] Reerences cued carry the particles through the conduit with the fluid move- UNITED STATES PATENTS ment therethrough.

2,950,353 8/1960 Fomenko 340/1741 I I I s /Z /7 3 I s I ,1 Z! Z4 :1 l Z/ j 7f Patent ed Dec. 28, 1911 3,631,423

2 Sheets-Sheet l M a 2; F54 F75: F0551 TORI ArraA/EVJ.

Patented Dec. 28, 1971 2 Sheets-Sheet 2 SELF-PURGING DISK SYSTEM BACKGROUND OF THE INVENTION Field of the Invention This invention relates to the removal of foreign particles from a closed system housing a rotating mass where the system is designed to have minimum foreign particles in the interior of the housing, and is particularly useful where the rotating mass is a magnetic disk memory.

In the design of numerous mechanical systems special attention must be directed to eliminating particles of foreign matter from the interior of the enclosure. Many systems are assembled in a clean room specially designed and tightly controlled to limit the foreign matter in the air therein. However, some contaminants are generally still present in the room, and in particular in the area of assembly, and these contaminants may find their way into the housing of the mechanical system. These particles may be very deleterious to the operation of the system, and it is thus desirable to eliminate even the limited number of foreign particles that may be present in the system after assembly. 7

One example of a closed mechanical system in which foreign particles can be disruptive is a disk file storage information system. A magnetic disk file memory is housed in a closed system and is generally assembled in a clean room to exclude foreign particles from the'interior of the housing to the greatest possible extent, because even a small number of particles may be damaging. In a magnetic disk file system the information is stored on the magnetic surface of the large disk which is rotatable in the housing and access to the magnetic surface is by way of magnetic transducers making up the read ing and writing head of the system in which the disk memory is employed. The magnetic transducers are necessarily positioned extremely close to the surface of the disk for most efficient magnetic coupling between the magnetic surface and the transducers. In one example, the transducers are only 60 microinches from the surface of the disk. Because of the close proximity of the transducers to the surface of the disk any foreign particles that are in the housing that find their way to the area between the transducers and the surface of the disk may destroy the operability of the system or at least substantially impair the reliability of the system.

SUMMARY OF THE INVENTION This invention involves a self-purging system or a system for removing particles over a selected size from the interior of an enclosure for a rotating mass wherein areas of different static pressure of the fluid enclosed in the enclosure are developed as the mass rotates, with a first area having a first static pressure and a second area having a second static pressure less than the first static pressure by an amount sufficient to carry the particles in the fluid from the first area to the second area through an external conduit, which external conduit includes a filter for collecting particles over a selected size. The combination is simple and relatively inexpensive for the benefits that may result from the removal of particles of foreign matter by use of pressure developed by the closed system itself.

The system is particularly useful in the self-purging of or the removing of particles over a selected size from the housing for a rotatable magnetic disk memory. For the purging of a housing for a rotatable magnetic disk memory the filter may advantageously collect all particles over microinches, for example.

BRIEF DESCRIPTION OF THE DRAWINGS These and other features and advantages of the present invention may be understood more clearly and fully upon consideration of the following specification and drawings, in which:

FIG. 1 is a front elevation view, partially broken away, of a closed system having a circular enclosure housing a circular rotating mass which has a self-purging system in accordance with the present invention;

FIG. 2 is a cross-sectional view of the closed system of FIG. 1, taken along section line 22 therein;

FIG. 3 is a front elevation view of a closed mechanical system having a rotating magnetic disk memory and incor porating a self-purging system in accordance with the present invention;

FIG. 4 is a cross-sectional view of the magnetic disk memory system of FIG. 3, taken along the section line 4-4 therein; and

FIG. 5 is a chart showing the static pressure distribution at a selected distance from the rotating magnetic disk at selected points in the rectangular cover of the enclosure of the system of FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1 there is shown a disk-shaped mass 1 that isrotatable in a housing 2 of a circular configuration and which completely encloses the mass 1 to form a closed system. It is assumed that the closed system of FIG. 1 was assembled in a clean room in an attempt to eliminate foreign particles from the interior of the housing 2. However, in practice, it is found that particles of foreign matter find their way into the interior of the housing even though the system was assembled in a clean room and these particles may cause failure of the closed system. Thus, it is desirable to remove any foreign particles that remain in the housing 2 after assembly.

In operation, the rotating mass 1, which is disk-shaped acts like a pump with a constant flow of fluid contained in the housing coming off the periphery of the disk. In such a system, as shown in FIG. 1, there is a constant high-pressure area .created near the disks outer diameter and a low-pressure area created near its center or axis of rotation.

An outlet port 3 is provided in the end wall 4 of the housing 2 adjacent to the high-pressure area near the outer periphery of the rotatable mass 1. An inlet port 5 is provided in the same end wall 4 adjacent the low-pressure area near the center of axis of rotation of the rotating mass 1. Alternatively, the inlet port may be located in the other end wall 8 of the housing 2 adjacent a low-pressure area in the housing.

The outlet port 3 and inlet port 5 are connected externally through a conduit 6 in which a filter 7 is located. The filter 7 is an absolute filter and collects all particles over a selected size. Thus, in operation, the rotating mass creates a high-pressure area near the outlet port 3, which is sufficiently different from the low-pressure area near the inlet port 5, that fluid, which may contain particles of foreign matter, will flow through the external conduit 6 and through filter 7 therein. The particles that are carried by the fluid will be trapped and retained by the filter 7 thereby effectuating a self-purging system for the closed system of FIGS. 1 and 2.

The self-purging system of the present invention was found to work very effectively on a closed magnetic disk file system for the removal of foreign particles that remained in the enclosure or housing for the system after assembly. The particular system on which the self-purging system was employed is representatively shown in FIGS. 3 and 4.

The closed magnetic disk file system of FIGS. 3 and 4 includes a rotatable magnetic disk 10 supported by a shaft II joumaled in bearings 12 and 13, which are schematically shown in FIG. 4. A housing 14 surrounds and encloses the disk 10.

Such magnetic disk memory systems are generally assembled in a clean room in an attempt to eliminate all particles of foreign matter from the interior of the housing 14. However, foreign matter may be left in the housing 14 when it is assembled around the magnetic disk file I0.

Additionally, there is the possibility that particles of foreign matter, in addition to those that may have been left in the housing at the time of assembly, may be generated during operation of the magnetic disk file system by possible chemical reactions, or possibly erosion of some type. It is desirable to remove the particles initially present in the system and any that may be generated while the system is in operation. For

this purpose, the self-purging system of the present invention, which does not require any external source of power, is advantageously adaptable. The self-purging system will be in operation whenever the disk file system is in operation. Thus, to remove any foreign particles that are free to move about in the enclosure or housing 14 of the magnetic disk file system of FIGS. 3 and 4, a self-purging system in accordance with the present invention is employed.

In the illustrative disk file system of FIGS. 3 and 4, the end walls 15 and 16, that are tangential to the axis of rotation of the magnetic disk 10, have two sections of differing configurations. As shown in FIG. 3, end wall 15 has a rectangular sec-' tion 17 and an arcuate section 18 that is a chord of a circle having its center at the center of the axis of rotation of the disk 10. The rectangular section 17 covers the majority of the face of the magnetic disk 10 and supports the journal bearings 12 and 13 for the shaft 11 about which the magnetic disk 10 rotates. The axis of rotation is represented by the cross 20 in FIG. 3.

The magnetic transducers, which provide access to the magnetic disk memory, are representatively shown by blocks 21 and 22 in FIGS. 3 and 4. Magnetic transducer block 21 is mounted on section 18 and magnetic transducer block 22 is mounted on arcuate section 23 of wall 16, to provide a balanced system.

The magnetic transducers in one illustrative example are positioned only 60 microinches from the face of the disk, which rotates at a relatively high speed of 1,750 revolutions per minute. The information is stored as individual bits in extremely close proximity and in very small spaces on the disk so that any particles of foreign matter that scratch the disk or lodge between a magnetic transducer and the disk may destroy some information, impede the accurate coupling or otherwise impair the desired high quality of the system.

In the particular magnetic disk file system represented in FIGS. 3 and 4, the distance between the arcuate sections 18 and 23 is different from the distance between the rectangular sections 16 and 17. As a consequence, the fluid in the housing 14 experiences a cross-sectional transition in its flow between sections 17 and 18 and sections 16 and 23. The arcuate section 18 has a flange 24 for mating with a flange 25 on the rectangular section 17 for joining the two sections to form the end wall 15. The rectangular section 17 may be made seperable from the remainder of the housing 14, or the housing may be separable in some other manner, to provide for insertion of the disk 10 in the housing 14. v

To find the best location for the ports of the self-purging system in the rectangular section, which section was best suited for the location of the ports in the particular system under consideration, pressure distribution and streamline directions were measured and determined at a distance of five-eighths inch from the face of the disk 10. The static pressure distribution in inches of water was then plotted on a chart, which is shown in FIG. 5. On this chart the distances from the axis of rotation 20 are indicated.

It is seen from the pressure distribution chart of FIG. 5 that the area 26 of highest measured pressure is near the flange 25 several minutes of operation the free particles in the interior were substantially reduced.

As an alternative to the'self-purging system shown in the drawings, the outlet port may be positioned in the sidewall rather than in an end wall. Additionally, the port may be designed to collect substantially all of the fluid at the periphery of the rotating mass. The outlet port may then be coupled through one or more filters to one or more inlet ports located on one or both sides of the rotating mass. Altematively, there may be two or more systems of the type shown in the drawing employed with a closed system with one or more selfpurging systems on each side of the rotating mass.

Various changes may be made in the details of construction without departing from the spirit and scope of the invention as defined by the appended claims.

What is claimed is:

1. A system for removing particles over a selected size from ambient fluid surrounding a magnetic disk, which comprises:

a rotatable magnetic disk;

means for rotating the disk, thereby developing in the ambient fluid adjacent the disk a static pressure distribution which has in a first area a substantially maximum static pressure and which has in a second area a substantially minimum static pressure;

a housing for enclosing a magnetic disk and the ambient fluid, the housing having end walls spaced apart from opposite faces of the disk and substantially parallel to the disk and having an outlet port and an inlet port in the end walls, the outlet port and the inlet port being located at said first and second areas respectively adjacent to the disk and between which areas the developed static pressure diflerential is sufficient to move ambient fluid through an external conduit with a filter;

a filter for collecting particles over a selected size; and

a conduit connecting a filter between the inlet port and the outlet port.

2. A system for removing particles over a selected size from fluid surrounding a magnetic disk, which comprises:

a rotatable magnetic disk;

a housing for enclosing the magnetic disk and the fluid, the

housing having an interior surface portion in an area adjacent the periphery of the disk and against which fluid impinges when the disk rotates, said interior surface portion communicating with the disk to provide a narrowing transition in the cross-sectional area in the direction through which the fluid flows thereby developing in the impinging fluid a static pressure head, an outlet port adjacent said portion for fluid flowing out of the housing, and an inlet port in an area adjacent the central portion of the disk for fluid flowing back into the housing;

a filter for collecting particles over a selected size; and

a conduit connecting a filter between the inlet port and the outlet port.

3. A system in accordance with claim 2 wherein the housing comprises an end wall having a section spaced apart from and substantially parallel to a surface of the disk in said area adjacent the periphery of the disk and wherein the outlet port is and the edge of the rectangular section 17 and that the area 27 located in the end wall in the area adjacent to said interior surof lowest pressure is also near the flange 25 and on the opposite side of the axis of rotation 20.

As seen in FIGS. 3 and 4, an outlet port 30 is located on rectangular section 17 adjacent the area 26 of high pressure face portion.

4. A system in accordance with claim 2 wherein the filter has means for collecting particles over one-half micron in size. 5. A system for removing particles over a selected size from and an inlet port 31 is located on rectangular section 17 adfluid surrounding a magnetic disk, which comprises:

jacent the area 27 of low pressure. A tube 32 connects the outlet port 30 to the inlet port 31, with an absolute filter 33 positioned between the ports.

The difference in static pressure developed by the rotating disk 10 of FIGS. 3 and 4 is approximately 1.23 inches of water which is sufficient to carry particles in the fluid through the tube 32 and into the filter 33 for the collection of particles therein. In one embodiment the filter 33 was an absolute filter that collected all particles over 20 microinches or approximately one-half micron in size and it was found that after a rotatable magnetic disk;

a housing for enclosing the magnetic disk and the fluid which flows when the disk is rotated, the housing having an end wall comprising a first section spaced a first distancefrom a surface of the disk, a second section spaced a second, closer distance from the same surface, and a joining part closing the two sections, the joining part at least partially spanning a chord between edges of the disk, the end wall communicating with the surface of the disk to provide a narrowing transition in the cross-secjacent the opposite side of the chord for fluid flowing back into the housing; a filter for collecting particles over a selected size; and

a conduit connecting the filter between the inlet port and the outlet port. 

1. A system for removing particles over a selected size from ambient fluid surrounding a magnetic disk, which comprises: a rotatable magnetic disk; means for rotating the disk, thereby developing in the ambient fluid adjacent the disk a static pressure distribution which has in a first area a substantially maximum static pressure and which has in a second area a substantially minimum static pressure; a housing for enclosing a magnetic disk and the ambient fluid, the housing having end walls spaced apart from opposite faces of the disk and substantially parallel to the disk and having an outlet port and an inlet port in the end walls, the outlet port and the inlet port being located at said first and second areas respectively adjacent to the disk and between which areas the developed static pressure differential is sufficient to move ambient fluid through an external conduit with a filter; a filter for collecting particles over a selected size; and a conduit connecting a filter between the inlet port and the outlet port.
 2. A system for removing particles over a selected size from fluid surrounding a magnetic disk, which comprises: a rotatable magnetic disk; a housing for enclosing the magnetic disk and the fluid, the housing having an interior surface portion in an area adjacent the periphery of the disk and against which fluid impinges when the disk rotates, said interior surface portion communicating with the disk to provide a narrowing transition in the cross-sectional area in the direction through which the fluid flows thereby developing in the impinging fluid a static presSure head, an outlet port adjacent said portion for fluid flowing out of the housing, and an inlet port in an area adjacent the central portion of the disk for fluid flowing back into the housing; a filter for collecting particles over a selected size; and a conduit connecting a filter between the inlet port and the outlet port.
 3. A system in accordance with claim 2 wherein the housing comprises an end wall having a section spaced apart from and substantially parallel to a surface of the disk in said area adjacent the periphery of the disk; and wherein the outlet port is located in the end wall in the area adjacent to said interior surface portion.
 4. A system in accordance with claim 2 wherein the filter has means for collecting particles over one-half micron in size.
 5. A system for removing particles over a selected size from fluid surrounding a magnetic disk, which comprises: a rotatable magnetic disk; a housing for enclosing the magnetic disk and the fluid which flows when the disk is rotated, the housing having an end wall comprising a first section spaced a first distance from a surface of the disk, a second section spaced a second, closer distance from the same surface, and a joining part closing the two sections, the joining part at least partially spanning a chord between edges of the disk, the end wall communicating with the surface of the disk to provide a narrowing transition in the cross-sectional areas through which the fluid flows on one side of the chord and to provide a corresponding opening transition on the other side of the chord so that a static pressure differential is developed between fluid flowing on opposite sides of the chord, an outlet port located in the end wall adjacent one side of the chord for fluid flowing out of the housing, and an inlet port located in the end wall adjacent the opposite side of the chord for fluid flowing back into the housing; a filter for collecting particles over a selected size; and a conduit connecting the filter between the inlet port and the outlet port. 